Today wind turbine blades are transported by trucks furnished with sophisticated and expensive special equipment. This is due to the weight and size of the blades, which continue to increase and is approaching lengths near 100 meters. Earlier, when the blades were shorter, an ordinary flatbed trailer could be used.
Known today is a way of transporting a blade as shown in Danish Patent 176923 B1, where a large frame is connected to the blade root. Hydraulic jacking equipment located on a truck is connected to the frame in order to lift, hold and draw the blade root for transport. Also, a non-driven dolly is used as a spanwise support for the blade tip. As the hydraulic jacking equipment is located as well as supported on the truck, the load from the blade weight on the truck becomes very high. This is critical with respect to axle pressure exerted by the truck on the road, which is limited by statute. Also, as the load is high and the truck, in such a configuration, has to be situated away from the blade root, the jacking equipment necessarily has to exert large forces and torque on the blade root and thereby on the blade.
Hence, a simplified method of transport would be advantageous, which decreases axle pressure on the vehicle and exert less force and torque on the blade, as well as a simplified method for stacking of blades for sea transport.
Also, as the offshore wind market is increasing, there is a need for improved stacking of blades for sea transport. One known method is described in U.S. Pat. No. 8,602,700, which shows a system of double frames, where inner frames alone is used for land transport and additional, outer frames along with the inner frames must be provided for stacking of blades for sea transport.
It is a further object of the present invention to provide an alternative to the earlier art.